1. Field of the Invention
This invention relates to a solar heat collector having minimum edge heat loss.
2. Discussion of the Technical Problems
The advantages of using solar heat collectors to collect solar energy for heating a fluid and/or for generating electric power have been recognized in the prior art.
In commonly assigned U.S. patent application Ser. No. 450,703 filed on Mar. 13, 1974, in the name of Pandit G. Patil and entitled "Solar Heat Collector Window", there is disclosed various embodiments of solar heat collectors that may be used to heat water.
In general, the solar heat collectors of the above-identified application include an outer glass plate, an intermediate glass plate and a solar energy absorber. A spacer assembly is provided between each of the cover plates and absorber. In general, each of the spacer assemblies include (1) a tubular metal spacer frame for maintaining the cover plates and absorber in spaced relation with airspaces therebetween; (2) a desiccant material in the spacer frames for absorbing moisture from the airspaces; and (3) a moisture-impervious adhesive between the spacer frames and adjacent cover plates and absorber to prevent moisture from moving into the airspaces.
Although the solar heat collectors disclosed in the above-identified application are ideally suitable for collecting solar radiation for subsequent use, there are limitations. For example, as the absorber is heated by solar radiation, the metal spacer frame adjacent the absorber is heated by conduction. This is because the moisture-impervious adhesive provided between the metal spacer frame and absorber is not a good thermal insulator. When the spacer frame is heated, heat is transmitted to the ambient air by convection which reduces the amount of heat that is available for use.
The loss of heat from the absorber to the metal space frame by conduction and the subsequent transfer of heat from the spacer frame to the ambient air by convection and/or radiation is termed edge heat loss.
It would be advantageous, therefore, if a solar heat collector was available that did not have the limitations of the prior art, more particularly, a solar heat collector that has minimum edge heat loss.